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Investigation of the Change in the Flavor of a Coffee Drink during Heat Processing

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Heat processing is responsible for the change in the flavor of a coffee drink. In this study, the application of gas chromatography-olfactometry of headspace samples (GCO-H) using the vapor fraction before and after heat processing of the coffee samples resulted in the detection of 12 odor-active peaks for which the flavor dilution (FD) factors changed. Eight potent odorants were identified from these peaks by gas chromatography-mass spectrometry (GC-MS). Among these components, methanethiol (putrid), acetic acid (sour), 3-methylbutanoic acid (sour), 2-furfuryl methyl disulfide (meaty), and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel-like) increased after heating of the coffee sample, whereas 2-furfurylthiol (roasty), methional (potato-like), and 3-mercapto-3-methylbutyl formate (roasty) decreased compared with the coffee sample before heat treatment. In addition, extensive studies have been carried out on the pH effects on the change in the concentration of 2-furfurylthiol during heat processing and in the pH range of 5-7; it was found that the concentration of this compound in the model solutions had significantly changed.

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... This market is mainly comprised of roasted, instant, and ready-to-drink (RTD) coffee [1]. The flavor of a roasted coffee brew is influenced by factors such as the geographical location of origin, variety, climatic factors, processing methods, roasting process, and preparation methods [2][3][4][5][6][7][8][9][10]. The differences in sensory properties can, in turn, affect consumers' preferences for and emotions or attitudes toward coffee drinking [11]. ...
... Trigonelline and proteins are broken down through Maillard reactions with sugars that are present in green beans to produce volatile compounds such as pyridines, pyrroles, and pyrazines ( Table 2). The pyrazines, pyrroles, and pyridines are responsible for aroma attributes such as nutty, roasted, and toasted notes in the coffee aroma [3][4][5]8,9,58,63,64]. Sulfurous, fresh coffee [4,5,9,78,79] Dulsat-Serra et al. [81] discussed the impact of thiols on the aroma and flavor of both roasted coffee and coffee brew. ...
... The pyrazines, pyrroles, and pyridines are responsible for aroma attributes such as nutty, roasted, and toasted notes in the coffee aroma [3][4][5]8,9,58,63,64]. Sulfurous, fresh coffee [4,5,9,78,79] Dulsat-Serra et al. [81] discussed the impact of thiols on the aroma and flavor of both roasted coffee and coffee brew. For example, 3-methyl-2-buten-1-thiol, a thiol with a low aroma threshold, was expressed by a skunky odor in brewed coffee [78]. ...
Article
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Flavor continues to be a driving force for coffee’s continued growth in the beverage market today. Studies have identified the sensory aspects and volatile and non-volatile compounds that characterize the flavor of different coffees. This review discusses aspects that influence coffee drinking and aspects such as environment, processing, and preparation that influence flavor. This summary of research studies employed sensory analysis (either descriptive and discrimination testing and or consumer testing) and chemical analysis to determine the impact aspects on coffee flavor.
... It was reported that coffee flavor changed during sterilization at 121 C for 15 minutes or at 134 C for 3 minutes. There were support studies showing that heating caused substantial degradation of FFT and MFT through oxidation and hydrolysis [90,91]. Kumazawa and Masuda [91] investigated the influence of heating processes on the change in the flavors of coffee drinks. ...
... There were support studies showing that heating caused substantial degradation of FFT and MFT through oxidation and hydrolysis [90,91]. Kumazawa and Masuda [91] investigated the influence of heating processes on the change in the flavors of coffee drinks. The sensory study showed that sterilization of a coffee drink at 121 C for 10 minutes in a can significantly decreased the potent roasty flavor of the fresh coffee drink [91]. ...
... Kumazawa and Masuda [91] investigated the influence of heating processes on the change in the flavors of coffee drinks. The sensory study showed that sterilization of a coffee drink at 121 C for 10 minutes in a can significantly decreased the potent roasty flavor of the fresh coffee drink [91]. The study also focused on the effects of pH, in the range of 3e7, on FFT concentration change during heat processing. ...
Article
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Flavor is the most important aspect of food. Based on the complex matrix of the food system and the flavor structure themselves, one important factor that plays a key role in the quality attribute of food is flavor stability. Not surprisingly, there is a large volume of published research investigating the stability of different food flavor compounds, since understanding flavor stability is crucial to creating greater awareness of dietary flavor application. This review presents a variety of factors that are thought to be involved in the stability of several selected important flavor compounds and the approach to improve the stability of different flavors. Some mechanisms of chemical degradation of flavor compounds were also provided.
... In particular, volatile thiols are extremely influential on the sensory profile of coffee, despite their low concentrations, due to their low odor thresholds (Sunarharum et al., 2014). Some of them, such as methanethiol (MT), 2-furanmethanethiol (2FMT), 3-mercapto-3methylbutanol (3MMB) and 3-mercapto-3-methylbutyl formate (3MMBF), have been described as key impact aroma compounds, often correlated to roasty, sulfurous and coffee notes (Kumazawa, & Masuda, 2003a, 2003bMayer, Czerny, & Grosch, 2000;Sanz, Czerny, Cid, & Schieberle, 2002;Sunarharum et al., 2014). Moreover, the depletion of thiols during coffee conservation has been associated with a decrease of its sensory quality (Charles-Bernard, Roberts, & Kraehenbuehl, 2005;Hofmann & Schieberle, 2002;Holscher & Steinhart, 1992;Mayer & Grosch, 2001). ...
... The analytical assay of volatile thiols in coffee is hindered by the complexity of the matrix, and by both their high reactivity and their typically low concentrations. The additional difficulty in analyzing coffee brew rather than coffee powder, comes from the reported instability of thiols after brewing, due to chemical interactions with other coffee components in aqueous solution (Charles-Bernard et al., 2005;Hofmann & Schieberle, 2002;Kumazawa & Masuda, 2003b). Current methods to assess thiols in brewed coffee require relatively large samples, they are in general laborious and timeconsuming, and some of them involve sample manipulation steps during which volatile thiols can be lost or undergo degradation. ...
... Moreover, the typical selenium isotopic pattern contributes to the selectivity of the method. The overall extraction and derivatization procedure is performed in 1 min, and if it is carried out immediately after the coffee is brewed, it allows volatile coffee thiols to be recovered, preventing their depletion due to interaction with other coffee components (Charles-Bernard et al., 2005;Hofmann and Schieberle, 2002;Kumazawa and Masuda, 2003b). ...
... In particular, 3-mercapto-3-methyl-1-butyl formate appeared comparable or even almost 10-fold more potent than 2-furfurylthiol (Blank et al., 1992; and methanethiol was described as the major contributor to the freshly roasted coffee aroma (Holscher & Steinhart, 1992). In brewed coffee, some AEDA results confirmed the higher sensory impact of 3-mercapto-3-methyl-1-butyl formate over the other thiols (Blank et al., 1992;Sanz, Czerny, Cid, & Schieberle, 2002;Kumazawa & Masuda, 2003a); while others indicated 2-furfurylthiol as the most relevant thiol Kumazawa & Masuda, 2003b). Meanwhile, 3-mercapto-3-methyl-1-butyl formate and 2-furfurylthiol were defined as potent odorants in coffee brews by CharmAnalysis™; but their impact was often lower than that of 3-methyl-buten-1-thiol (Akiyama et al., 2008). ...
... Finally, the degradation of 3-mercapto-3-methyl-1-butyl formate and acetate observed in thermally-treated coffee drinks has been attributed to the hydrolysis of the esters with the production of 3-mercapto-3-methyl-1-butanol (Kumazawa & Masuda, 2003b). ...
... First, although all thiols decrease in the presence of melanoidins, the most pronounced effects have been observed for 2-furfurylthiol (Hofmann & Schieberle, 2002). Likewise, the formic acid ester of 3-mercapto-3methyl-1-butanol showed a lower thermal stability and a higher pH dependence than the corresponding acetic acid ester, which was ascribed to its molecular structure (Kumazawa & Masuda, 2003b). ...
Article
Thiols are among the compounds that have the greatest impact on the flavor of coffee. Due to their extremely low odour thresholds, they have a significant sensory impact even at very low concentrations. Thiols are formed during coffee roasting and are described as the key odorants responsible for the typical “coffee” and “roasty” odour notes, greatly influencing the sensory characteristics of coffee. They are particularly reactive and prone to oxidation; their rapid depletion after preparation of a coffee brew and during storage of roasted coffee has been associated with sensory quality decrease and coffee going stale. For these reasons, their determination and insight into their formation and degradation mechanisms could help us to preserve the sensory quality of coffee and to modulate its sensory features. Coffee aroma has been widely studied in recent decades, and it has become evident that the role of certain volatile thiols is paramount. Nevertheless, a limited number of studies have specifically addressed this class of compounds, and several aspects have not yet been satisfactorily elucidated. The aim of this review is to provide an overview of the current state on knowledge about coffee thiols, focusing on their occurrence, determination, sensory impact, formation and evolution in roasted and brewed coffee.
... RTD coffee requires additional processing 2 of 16 and storage and therefore faces challenges with flavor stability [15]. For example, the decrease in roasty odor notes of RTD coffee after heat processing has been attributed to the degradation of unstable odorants containing the thiol functional group [16,17]. Similarly, Murakami et al. [18] reported that the overall coffee flavor, coffee aroma, and bitterness of canned coffee drinks were weaker in intensity after the sterilization process. ...
... However, changes in the aroma volatility and stability would be expected. Some potent well-known coffee odorants such as 2-furfurylthiol and 3-mercapto-3-methylbutyl esters have shown pH dependence in RTD coffee drinks [17,67]. ...
Article
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Coffee brew flavor is known to degrade during storage. Untargeted and targeted LC/MS flavoromics analysis was applied to identify chemical compounds generated during storage that impacted the flavor stability of ready-to-drink (RTD) coffee. MS chemical profiles for sixteen RTD coffee samples stored for 0, 1, 2, and 4 months at 30 °C were modeled against the sensory degree of difference (DOD) scores by orthogonal partial least squares (OPLS) with good fit and predictive ability. Five highly predictive untargeted chemical features positively correlated to DOD were subsequently identified as 3-caffeoylquinic acid, 4-caffeoylquinic acid, 5-caffeoylquinic acid, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid. The increase in the six acidic compounds during storage was confirmed by sensory recombination tests to significantly impact the flavor stability of RTD coffee during storage. A decrease in pH, rather than an increase in total acidity, was supported to impact the coffee flavor profile.
... Flavor and aroma are arguably the most important sensory attributes of coffee beverage quality [19] and, not surprisingly, they have been the target of numerous studies. Over 100 different compounds have been detected in green coffee beans and more than 800 volatiles were identified in roasted beans [19]. ...
... Flavor and aroma are arguably the most important sensory attributes of coffee beverage quality [19] and, not surprisingly, they have been the target of numerous studies. Over 100 different compounds have been detected in green coffee beans and more than 800 volatiles were identified in roasted beans [19]. The volatile compounds come from several sources, including original bean components, compounds formed through the bean metabolism after harvest, fermentation (if performed) and roasting [2]. ...
Article
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This study investigates the impact of wet fermentation on flavor volatiles and sensory quality of coffee beans and beverage. Pulped coffee beans were kept underwater for 36 h before air-drying and roasting, and volatiles in the beans were characterized by solid-phase microextraction and gas chromatography–mass spectrometry. A total of 79 volatiles were identified. Fermented roasted beans had higher concentrations of ethanol, isoamyl alcohol, 3-methylbutanal, benzaldehyde, acetaldehyde, and ethyl acetate compared with mechanically processed (no fermentation) beans; whereas, ketones, pyrazines, pyrroles, pyridines, furans and sulfides were not significantly different between the two treatments. Coffee made with fermented beans was rated significantly higher in flavor, aroma, acidity, body and uniformity scores with noted fruity aroma compared with beverage made with mechanically processed beans in sensory evaluation (cup test) by a 3 Q-Grade Coffee Certification Panel. The findings demonstrated wet fermentation played an important role in coffee flavor, aroma and sensory quality.
... 2-Methyl-3furanthiol (meaty), an odorant presenting a high flavor dilution factor [19] was observed in all four samples. 2-Furfurythiol (sulfur group), whose flavor dilution factor is also high, is an odorant commonly found in coffee [20,21] and roasted peanuts [17]. It was observed only in oil samples prepared from roasted kernels (RK, GRK). ...
... It was observed only in oil samples prepared from roasted kernels (RK, GRK). This was somehow surprising since 2-furfurythiol has been shown to be heat-unstable [20]. However, this instability has only been studied in aqueous solution where it has been shown to be pH dependent. ...
Article
Argan tree (Argania spinosa (L.) Skeels) is endemic in Morocco. The aroma compounds of argan oil prepared from roasted and unroasted argan kernels were analyzed using GC-MS and olfactometry. Influence of the fruit peeling method on the olfactometric parameters was also studied. Oil coming from unroasted kernels furnished fourteen compounds if the fruits had been mechanically-peeled fruits (uRK), and twenty two when the kernels had been goat digested (GuRK). Thirteen compounds were common to the two studies. The oil obtained from roasted kernels of mechanically-peeled fruits (RK) furnished nineteen compounds. Twenty one were isolated from the oil obtained from roasted kernels of goat digested fruits (GRK). Twelve compounds were common to the two analyses. In all oil samples, the aldehyde/ketone derivatives composed the largest group of odorants. Acetophenone and p-methylacetophenone appear to be the most important contributors to the RK oil aroma. The unpleasant smell presented by argan oil prepared from naturally-peeled argan fruits (GuRK, GRK) could result from the presence of one or two odorants presenting a rancid odor.
... The high number of coffee drink lovers is due to multiple factors. Two of the major factors are the flavor and typical aroma of the coffee (Kumazawa & Masuda, 2003). ...
... Roasting is carried out in order to obtain the organoleptic properties (taste, color and unique structure) and volatile compounds (aldehydes, ketones, acetic acid, and formic acid) (Illy, 1998;Hernández et al., 2007), which represent the desired trait of the coffee. During roasting, coffee beans undergo a reaction that results in changes in physical properties (color, volume and density) and chemical composition (release of CO 2 , evaporation of water and volatile compounds) (Illy, 1998;Kumazawa & Masuda, 2003). Thus, the composition of volatile and other compounds in green coffee beans is important in determining the characteristics of coffee aroma. ...
Article
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This study was aimed to improve the quality of aroma of roasted coffee by using Taguchi's design as experimental technique. The roaster parameters evaluated were temperature, incubation time, moisture content and cylinder rotational speed. An orthogonal array L9, signal to noise ratio and ANOVA were employed to investigate the influence of the roaster parameters. The results showed that the optimal roasted coffee aroma was produced at a temperature of 170◦C, incubation time of 14 minutes, moisture content of 6% (v/w) and cylinder rotational speed of 50 rpm. The most to less significant roasting parameters as observed in this study were as follows: temperature, incubation time, moisture content and cylinder rotational speed. Furthermore, the results showed that the Taguchi design was better than the full experimental design in solving experiments with a minimum number. Keywords: ANOVA, Coffee roaster, Roasted coffee aroma, Signal to noise ratio, Taguchi technique
... Caramel, sweet, warm, and burnt characters were also welldetected aroma categories. The presence of 4-hydroxy-2,5dimethyl-3(2H)-furanone (Furaneol), although this component has been detected only as a small peak by FID detection, provided a strong cotton candy aroma (9,(14)(15)(16). The other compound that should be responsible for this aroma impression was 4,5-dimethyldihydro-2(3H)-furanone. ...
Article
Three cultivars of snake fruits, Pondoh Hitam, Pondoh Super, and Gading, were freshly extracted using liquid-liquid extraction. The aroma compounds of the three samples were analyzed by GC-MS and GC-olfactometry using the nasal impact frequency (NIF) method. A total of 24 odor-active compounds were associated with the aroma of snake fruit. Methyl 3-methylpentanoate was regarded as the character impact odorant of typical snake fruit aroma. 2-Methylbutanoic acid, 3-methylpentanoic acid, and an unknown odorant with very high intensity were found to be responsible for the snake fruit's sweaty odor. Other odorants including methyl 3-methyl-2-butenoate (overripe fruity, ethereal), methyl 3-methyl-2-pentenoate (ethereal, strong green, woody), and 2,5-dimethyl-4-hydroxy-3[2]-furanone (caramel, sweet, cotton candy-like) contribute to the overall aroma of snake fruit. Methyl dihydrojasmonate and isoeugenol, which also have odor impact, were identified for the first time as snake fruit volatiles. The main differences between the aroma of Pondoh and Gading cultivars could be attributed to the olfactory attributes (metallic, chemical, rubbery, strong green, and woody), which were perceived by most of the panelists in the Pondoh samples but were not detected in the Gading samples. This work is a prerequisite for effective selection of salak genotypes with optimal aroma profiles for high consumer acceptance.
... This process is time-temperature dependent and leads to several changes in the chemical composition and biological activities of coffee as a result of the transformation of naturally occurring polyphenolic constituents into a complex mixture of Maillard reaction products (Czerny et al. 1999;Sacchetti et al. 2009), as well as the formation of organic compounds resulting from pyrolysis (Daglia et al. 2000). Sulfur compounds are also changed by oxidation, thermal degradation, and/or hydrolysis (Kumazawa and Masuda 2003), and the vanillin content increases considerably during the roasting process (Czerny and Grosch 2000). Besides the chemical reactions during coffee roasting, moisture loss and other major changes (color, volume, mass, form, pH, density, and volatile components) occur, while CO 2 is generated (Hernández et al. 2008). ...
Article
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Coffee is one of the most consumed beverages in the world and is the second largest traded commodity after petroleum. Due to the great demand of this product, large amounts of residues are generated in the coffee industry, which are toxic and represent serious environmental problems. Coffee silverskin and spent coffee grounds are the main coffee industry residues, obtained during the beans roasting, and the process to prepare “instant coffee”, respectively. Recently, some attempts have been made to use these residues for energy or value-added compounds production, as strategies to reduce their toxicity levels, while adding value to them. The present article provides an overview regarding coffee and its main industrial residues. In a first part, the composition of beans and their processing, as well as data about the coffee world production and exportation, are presented. In the sequence, the characteristics, chemical composition, and application of the main coffee industry residues are reviewed. Based on these data, it was concluded that coffee may be considered as one of the most valuable primary products in world trade, crucial to the economies and politics of many developing countries since its cultivation, processing, trading, transportation, and marketing provide employment for millions of people. As a consequence of this big market, the reuse of the main coffee industry residues is of large importance from environmental and economical viewpoints. KeywordsCoffee–Silverskin–Spent grounds–Cellulose–Hemicellulose
... 커피향미에 관여하는 성분도 아주 복잡하다. 일반적으로 coffee bean을 roasting하면 휘발성 물질인 methanethiol, acetic acid, 3-methyl-butanoic acid, 2-furfuryl methyl disulfide, 4-hydroxy-2,5-dimethyl-3(2H)-furanone 등은 증가하고 2-furfurylthiol, methional, 3-mercapto-3-methyl butyl formate 등 은 감소하였다[15]. 비 휘발성 물질인 arginine, cysteine, lysine, serine과 같은 유리 아미노산은 파괴되고 탄수화물, sucrose, arabinogalactan 등도 파괴되어 coffee의 맛과 향에 관여 하는 것으로 보고되어 있다[18,28]. 또한 커피의 향미는 커피 에 존재하는 향미성분의 복잡한 조합에 의해 부여되며, roasting 정도(시간, 온도)에 따라 상이한 향미를 나타내기 때문에, 이와 같은 커피 향미변화는 GTL을 커피생산 조건과 유사하게 roasting함으로써 CLGT를 생산할 수 있을 것임을 시사한다. ...
Article
The cytotoxicity of coffee-like green tea (CLGT) was determined in a human breast cancer cell line, MCF-7; a human prostate cancer cell clone, PC-3; a human neuroblastoma cell line, SK-N-SH; and a rat cardiomyoblast cell line, H9c2, with reference to green tea leaves (GTL). The CLGT was prepared by roasting the GTL for 60 min at in a temperature-controlled frying pan. The CLGT preparation imitated the flavor and taste characteristics of coffee fairly well according to sensory analysis. The CLGT preparation had no adverse cytotoxic effects on the cancer cells or the normal cells compared to GTL. No significant change in the antioxidant activity was seen in the CLGT preparation compared to that of GTL. The amount of total protein, sugar, and phenolic compounds was reduced in the preparation relative to those in GTL, a fact that might explain the coffee-like flavor and/or taste characteristics of the CLGT preparation. These results suggest that CLGT prepared by roasting GTL for 60 min at does not show any adverse effects on cancer cells and normal cells compared to GTL. They imply that CLGT could be safe for human consumption.
... Eighty-two compounds were tentatively identified with the cross search in a list of 658 candidates with the NIST AMDIS search of the TIC obtained from MVM. Finally, 82 aroma compounds were further filtered with keywords of "coffee" (in the title) and "DB-Wax" (used for GC analysis) in the literature data compiled in Aroma Office 2 D database and 67 compounds were previously reported in these data [17][18][19][20][21][22]. Table 2 summarizes the 82 aroma Table 2 Identified compounds and corresponding vapor pressure, probability based matching (PBM), linear retention indices (LRI) and average LRI in the literature, Selected ions, repeatability, linearity, concentration, and ratios of calibration methods obtained for MVM-GC-MS analysis of coffee. ...
Article
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A novel multi-volatile method (MVM) using sequential dynamic headspace (DHS) sampling for analysis of aroma compounds in aqueous sample was developed. The MVM consists of three different DHS method parameters sets including choice of the replaceable adsorbent trap. The first DHS sampling at 25 °C using a carbon-based adsorbent trap targets very volatile solutes with high vapor pressure (>20 kPa). The second DHS sampling at 25 °C using the same type of carbon-based adsorbent trap targets volatile solutes with moderate vapor pressure (1-20 kPa). The third DHS sampling using a Tenax TA trap at 80 °C targets solutes with low vapor pressure (<1 kPa) and/or hydrophilic characteristics. After the 3 sequential DHS samplings using the same HS vial, the three traps are sequentially desorbed with thermal desorption in reverse order of the DHS sampling and the desorbed compounds are trapped and concentrated in a programmed temperature vaporizing (PTV) inlet and subsequently analyzed in a single GC-MS run. Recoveries of the 21 test aroma compounds for each DHS sampling and the combined MVM procedure were evaluated as a function of vapor pressure in the range of 0.000088-120 kPa. The MVM provided very good recoveries in the range of 91-111%. The method showed good linearity (r2 > 0.9910) and high sensitivity (limit of detection: 1.0-7.5 ng mL−1) even with MS scan mode. The feasibility and benefit of the method was demonstrated with analysis of a wide variety of aroma compounds in brewed coffee. Ten potent aroma compounds from top-note to base-note (acetaldehyde, 2,3-butanedione, 4-ethyl guaiacol, furaneol, guaiacol, 3-methyl butanal, 2,3-pentanedione, 2,3,5-trimethyl pyrazine, vanillin, and 4-vinyl guaiacol) could be identified together with an additional 72 aroma compounds. Thirty compounds including 9 potent aroma compounds were quantified in the range of 74-4300 ng mL−1 (RSD < 10%, n = 5).
... CLCs, due to their water content, require of a pasteurized or a sterilized process to prevent microbial spoilage [3][4][5]. Furthermore, common additives such as antifungals, pH controllers, and special packages have been implemented to maintain sensory characteristics with minimal changes in the profile during the long-term storage time [6,7]. The shelf life claimed by commercial products varies between 3 and 6 months, depending on the addition or not of additives and the solid soluble contents [1]. ...
Article
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Concentrated liquid coffees (CLCs) refer to stored extracts stable at environmental temperature, used as ingredients in the retail market. Their low chemical stability affects the sensory profile. This study was performed in two CLCs, one without additives (BIB) and another with a mix of sodium benzoate and potassium sorbate additives (SD), stored at 25 °C for one year. Quantitative-Descriptive (QDA) and discriminant analyses permitted identifying the critical sensory attributes and their evolution over time. The concentrate without additives presented an acceptance limit of 196 days (evaluated at a 50% acceptance ratio), while the additives increased the shelf life up to 226 days (38.9% improvement). The rejection was related to a decreased aroma, increased acidity, and reduced bitterness. A bootstrapped feature selection version of Partial Least Square analysis further demonstrated that reactions of 5-caffeoylquinic acid (5CQA) and 3,5-dicaffeoylquinic acid (3,5diCQA) could cause changes in the aroma at the first degradation stage. In the following stages, changes in fructose and stearic acid contents, a key indicator of acceptance for both extracts possibly related to non-enzymatic reactions involving fructose and other compounds, might affect the bitterness and acidity. These results provided valuable information to understand flavor degradation in CLCs.
... The identification of 2-FFT was carried out using GC-MS by the comparison of the ion spectra from authentic standards, the NIST data library and Kovats retention index (KI). The KI value was calculated based on a series of n-alkanes (C6-C40), and the result (1434) was similar to that of the previous reports (Kumazawa and Masuda 2003). The abundance of characteristic ions 45, 53, 81 and 114 ( Fig. 1) was compared with standard and library and showed that 2-FFT was successfully identified. ...
Article
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A reliable and sensitive method was developed to quantify the free 2-furfurylthiol (2-FFT) in coffee brew. Using cysteine addition combined with vacuum distillation, a coffee model with trace 2-FFT and similar physicochemical properties as coffee brew was prepared for standard curve construction. During the model preparation, 2-FFT in bound form was released to free 2-FFT and removed from coffee brew through vacuum distillation. The method sensitivity, precision, accuracy and selectivity were evaluated. The limit of quantification (LOQ) was 3.0 μg/L. The coefficient of variation (CV) was 7.1%. The average recovery rates were 86.8–106.2% at spiked concentrations of 22.6, 135.8 and 181 μg/L. Coffee brews prepared using Robusta and Arabica roasted coffee beans were analyzed, and results showed that coffee brew from Robusta coffee beans had a greater amount of free 2-FFT (20.94 μg/L) than Arabica coffee beans from Yunnan (11.34 μg/L) and Columbia (15.33 μg/L), respectively. This method would be beneficial to investigate the free amount of 2-FFT in coffee brew and the sensorial assay based on free 2-FFT concentration.
... Some authors (Kumazawa, & Masuda, 2003) have reported that heat processing affects the 305 aroma of coffee drinks. However, in this work, at the beginning of the study significant lower 306 areas in UHT treated coffee brews were only found for 2-butanone and 2,3-butanedione. ...
Article
In this work, the influence of an Ultra High Temperature (UHT) treatment on chemical and sensory composition of Arabica coffee brews for a longer shelf-life has been studied. A temperature of 120°C for 2s allows to obtain a microbiologically safe coffee brew, good valued from the sensory point of view. The behavior of the UHT vs non UHT treated coffee brew was followed throughout 120days of storage at 4°C. The UHT treatment keeps the typical acidity of the brews longer, delaying and softening the pH decrease and the development of sourness, which is one of the main causes for the rejection of stored coffee brews. The UHT treatment hardly affects the concentrations of caffeine and trigonelline, and of some phenolic compounds such as 5-caffeoylquinic (5-CQA), caffeic or ferulic acids. Sixteen key odorants and staling volatiles were analyzed by HS–GC–MS and lower changes were observed in the UHT treated coffee brew throughout storage. Higher DPPH scavenging activity was observed in the UHT treated coffee brew from days 60 to 120. In conclusion, the application of an UHT treatment is proposed to extend the shelf-life (up to 60days) of stored coffee brews.
... Seeventer et al. (2001) investigated the stability of thiols produced from model system ribose/cystein, and stated that 2-furfurylthiol, 2-mercapto-3-butanone, 2-methyl-3-furanthiol and furaneol declined at some stage in storage. In brewed coffee, after application of heat, the amount 2-furfurylthiol, methional, and 3-mercapto-3-methylbutyl formate was reduced, and it has been based on interactions with melanoidins ( Hofmann et al. 2001;Hofmann and Schieberle 2002;Kumazawa and Masuda 2003). The detriment of 2-furfurylthiol was associated to fenton-type oxidation on heating at 37°C for 1 hour ( Blank et al. 2002). ...
... In addition, adjustment of the pH of coffee-milk based beverages is an important technique in the production of canned coffee drinks. Such pH adjustments prevent clouding caused by an increase in acid levels during heat sterilization of coffee and prevent milk from curdling in the coffee-milk based coffee beverages (Kumazawa & Masuda, 2003). ...
Article
An in vitro gastrointestinal digestion model was used to investigate the effects of milk matrix: skimmed milk (Sm), whole milk (Wm) and processing methods: pH adjustment, high pressure homogenization processing (HPHP), thermal treatment (TT) on the antioxidant capacity, phenolics bioaccessibility of coffee. Our findings showed that the antioxidant capacity of all the samples decreased or unchanged after in vitro digestion. The total phenolic bioaccessibility of coffee (C), coffee with whole milk (Cwm), and coffee with skimmed milk (Csm) decreased by 29.2%, 28.5%, 21.1% from the HPHP treatment and by 14.7%, 34.2%, and 33.8% from TT, respectively. pH adjustment had little effect on the total phenolic bioaccessibility of Cwm and Csm but significantly decreased that of C. Wm showed better protective effect on the phenolic bioaccessibility than Sm. These results may contribute to the optimization of formulations and processing methods in coffee beverage production, thereby increasing the health benefits of coffee.
... pH is important for 2-FFT formation and loss in coffee brew. High pH conditions favor the formation of 2-FFT during coffee roasting and also increased 2-FFT loss during heating in model systems (Hofmann & Schieberle, 1998;Kumazawa & Masuda, 2003). However, the impact of pH on coffee aroma binding in coffee brews, and the relative understanding of free: bound 2-FFT in the coffee brew and their relative stabilities are not well understood and is therefore the focus of this study. ...
... This specific chemical motif may example the observed compound activity to increase the coffee cup score. In its free form, compound 3-methylbutanoic acid has been identified as a potent odorant in roasted coffee, exhibiting odor qualities such as sweaty and fermented (Blank, Sen, & Grosch, 1991;Holscher, Vitzthum, & Steinhart, 1990) and was suggested to contribute to the sour flavor of heated canned coffee drinks (Kumazawa & Masuda, 2003). Approximately a 3-fold higher odor activity of 3methylbutanoic acid (based on FD-factor) was reported in Arabica coffee compared to Robusta coffee (Blank et al., 1991). ...
Article
Untargeted LC/MS flavoromic profiling was utilized to identify compounds that positively impact coffee quality. The chemical profiles of eighteen coffee samples and the corresponding Specialty Coffee Association (SCA) cup scores were modeled by orthogonal partial least squares (OPLS) analysis with good fit and predictive ability (R2Y > 0.9, Q2 > 0.9). Four highly predictive chemical compounds positively correlated to cup score were subsequently isolated and purified (>90%) by multi-dimensional preparative LC/MS fractionation. Sensory recombination analysis by certified SCA Q-graders (n = 5) confirmed three out of four compounds significantly increased cup score when added to a control coffee (p < 0.001). Based on accurate mass spectrometry and NMR experiments, the compound structures were identified as novel compounds 3-O-caffeoyl-4-O-3-methylbutanoylquinic acid, and the corresponding lactone 3-O-caffeoyl-4-O-3-methylbutanoyl-1,5-quinide, as well as an unknown phenolic derivative containing a 3-methylbutanoyl moiety ([M-H]-1, m/z 671). No direct flavor activity was observed for each compound, indicating these compounds act as flavor-modifiers.
... Coffee is often combined with various ingredients such as sugar, honey, milk, citrus, ice, cream, and stabilizers, amongst which milk is the most popular added ingredient. However, the production of coffee-milk drinks (especially, the canned products) requires a series of processing steps and beverage formulations (e.g., the adjustment of pH) (Kumazawa and Masuda 2003). Moreover, the bioaccessibility of bioactive compounds can be influenced by several factors such as digestive enzymes, food matrix, and host-related factors (e.g., the initial content and properties of bioactive compounds) (Quan et al. 2020). ...
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To date, there exists a debate on the effect of milk added to coffee infusions/beverages concerning the nutritional quality of coffee and the functional properties of its phenolic compounds. Yet, the full nutritional quality and functional properties of a coffee beverage without a significant negative impact on its sensorial profile are highly desired by the consumers. Negative/masking, positive, and neutral effects of milk on the antioxidant activity and bioavailability of coffee phenolics (particularly, chlorogenic acids) have been reported. Some potential factors including the type and amount of milk added, type of coffee beverage, the composition of both milk (protein and fat) and coffee (phenolic compounds), preparation method, assays used to measure antioxidant properties, and sampling size may account for the various reported findings. Interactions between phenolic compounds in coffee and milk proteins could account as the main responsible aspect for the reported masking/negative impact of milk on the antioxidant activity and bioaccessibility/bioavailability of coffee bioactives. However, considering the interactions between milk components and coffee phenolics, which result in the loss of their functionality, the role of milk fat globules and the milk fat globule membrane can also be crucial, but this has not been addressed in the literature so far. • Highlights • In most cases, milk is added to the coffee beverages in several various ways. • Effect of milk on the nutritional/functional properties of coffee is controversial. • Enough evidence suggests negative effects of milk addition on properties of coffee. • Interactions of coffee phenolics and milk proteins could account as the main aspect. • The role of milk fat globules and milk fat globule membrane may also be crucial.
... Thus, comparing other brewed coffee such as Colombia and Kenya known to have distinct characteristics, blending samples might have relatively balanced characteristics resulted from blending. Besides, although RTD samples were also composed of various variety of coffee beans like the blended samples, thermal process such as sterilization could also influence coffee flavor [32], causing different profiles unlike blending samples. ...
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The aim of this study was to investigate consumers' acceptability and perceived sensory attributes of cold brew coffee, which is increasing in popularity. A total of 120 consumers evaluated liking of 13 cold brew coffee samples and checked sensory attributes they perceived using the check-all-that-apply (CATA) method. Correspondence analysis identified characteristics of each cold brew sample and brewing methods, namely cold brew, coffee machine brewed but served cold, ready-to-drink, and purchased from a coffee shop. In addition, a reduced number of terms were reviewed for common-to-all cold brew samples (17 terms) and specific to each sample (48 terms), which also discriminated among samples. Furthermore, data on consumers' liking were not influenced by caffeine contents and most of the volatile compounds, but chlorogenic acid and trigonelline contents were negatively related with sensory data. This study specifies the characteristics of cold brew coffee using the CATA method, shows consumers' segmentation using acceptability, and investigates the relationship between sensory liking data and non-volatile, volatile compounds of coffee.
... Seeventer et al. (2001) investigated the stability of thiols produced from model system ribose/cystein, and stated that 2-furfurylthiol, 2-mercapto-3-butanone, 2-methyl-3-furanthiol and furaneol declined at some stage in storage. In brewed coffee, after application of heat, the amount 2-furfurylthiol, methional, and 3-mercapto-3-methylbutyl formate was reduced, and it has been based on interactions with melanoidins ( Hofmann et al. 2001;Hofmann and Schieberle 2002;Kumazawa and Masuda 2003). The detriment of 2-furfurylthiol was associated to fenton-type oxidation on heating at 37°C for 1 hour ( Blank et al. 2002). ...
... Usefulness of freshly processed coffee is more because of its higher viability [60] besides of its active metabolism [95,96]. Hydrolysis and oxidation also affect the different compounds present in coffee [66]. Due to roasting of coffee, vanillin content were increased [31] as well as physical properties of coffee (e.g., color, texture, density and different volatile compounds, etc.) has also influenced [58]. ...
... Seeventer et al. (2001) investigated the stability of thiols produced from model system ribose/cystein, and stated that 2-furfurylthiol, 2-mercapto-3-butanone, 2-methyl-3-furanthiol and furaneol declined at some stage in storage. In brewed coffee, after application of heat, the amount 2-furfurylthiol, methional, and 3-mercapto-3-methylbutyl formate was reduced, and it has been based on interactions with melanoidins (Hofmann et al. 2001;Hofmann and Schieberle 2002;Kumazawa and Masuda 2003). The detriment of 2-furfurylthiol was associated to fenton-type oxidation on heating at 37°C for 1 hour (Blank et al. 2002). ...
... Specifically, RTD samples, except BaristaRTD, generally had lower contents of most volatile compounds, which corresponded with non-volatile compounds, showing the lowest contents in RTD samples. Kumazawa and Masuda [34] suggested that heat treatment for sterilization could affect the sensory aspect of canned coffee. The results of sensory evaluation showed significant differences between heated coffee and non-heated coffee samples. ...
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This study investigated the non-volatile and volatile compounds in samples of cold brew (CB) coffee, coffee from a coffee shop (CS), ready-to-drink (RTD) coffee, and brewed coffee from a coffee maker (CM). The volatile compounds were identified using headspace solid-phase microextraction with gas chromatography-mass spectrometry, and the samples were treated with high-performance liquid chromatography for the quantification of caffeine, chlorogenic acid, and trigonelline. The results indicate that RTD coffee had the lowest amounts of non-volatile compounds. A total of 36 volatile compounds were semi-quantified; the contents of most volatile compounds in CS and Folgers samples were higher than those in CB and CM samples. The contents of 25 volatile compounds in the CM sample were higher than those in the CB sample. The consumer and instrumental data show that the bitterness intensity was correlated with pyrazines, pyrroles, and guaiacols, whereas the coffeeID intensity was correlated with phenols. Semi-quantification and principal component analysis results show that the extraction method and temperature could influence the volatile compound profiles.
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The effects of heating time on physical changes (weight, volume, texture and colour) of coffee beans (Outspan and Guaxupe coffee) were investigated. The roasting temperature of both samples was 170°C and samples for analysis were taken at the intervals of 7 minutes during 40 minutes of roasting. Total weight loss at the end of the roasting process was 14.43 % (light roasted) and 17.15 % (medium to dark roasted) for Outspan and Guaxupe coffee beans, respectively. Significant (P < 0.05) changes in the coffee bean breaking force values were noted between the 7th and 14th minutes, and statistically not significant (P > 0.05) between the 35th and 40th minutes of the roasting. According to the L* colour parameter as a criterion for the classification of roasted coffee colour (light, medium, dark), the Outspan sample was medium and Guaxupe sample was dark roasted.
Chapter
Flavor compound methional in foodsFormation of methionalSynthesis of Met in plantsBiotechnology to enhance Met and methionalReferences
Article
Static headspace gas chromatography coupled to mass spectrometry (SHGC–MS) was used to identify aroma compounds in coffee pad powder. Based on the peak areas of these aroma compounds, the influence of the type of original package on the time of evolution was studied. Statistical ANOVA indicated that coffee pads which were individually packed and hermetically sealed lost less aroma compounds than did pads which were enclosed together in an open package. In addition, coffee pads from an open package were stored in closed plastic bottles at two different temperatures. Storing the pads at 4 °C instead of keeping them at room temperature had a positive influence on the evolution of aroma compounds with time.
Article
This study is the second of two publications that investigate the interactions between volatile and nonvolatile components in coffee brew. The purpose here was to shed some light into the chemical mechanisms responsible for the decrease of volatile thiols when in contact with coffee nonvolatiles. A mixture of volatile thiols covering a large range of physicochemical properties was monitored over time in the presence of a coffee brew model. The binding potential was estimated by SPME-GC-MS. Additives inhibiting specific reaction pathways were preincubated with the coffee brew 1 h prior to addition of the volatile compounds. Degradation kinetics of the volatile thiols were characterized by their rate constants k(obs). The effect of individual additives was shown by calculating k(rel), the relative rate constant as compared to the reference without additive. The conclusion was that thiols, mainly responsible for the "roasty" and "burnt" notes, disappear via two main chemical mechanisms. The results suggest that nucleophilic addition is the major pathway for thiol degradation. Addition occurs on oxidized species generated in the matrix in the presence of air. This mechanism prevails for aliphatic thiols (e.g., ethanethiol, methanethiol). Benzylic thiols (such as 2-furfurylthiol) can react in parallel via another pathway that is slowed in the absence of oxygen and in the presence of a radical scavenger. This points to a radical mechanism, but further work is needed to support this hypothesis. A direct correlation between thiol hydrophobicity and the magnitude of the interactions was shown as well. Therefore, weak physical interactions or hydrophobic assistance accelerating chemical reactions cannot be excluded at this point of the study.
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During the roasting process, coffee bean components undergo structural changes leading to the formation of melanoidins, which are defined as high molecular weight nitrogenous and brown-colored compounds. As coffee brew is one of the main sources of melanoidins in the human diet, their health implications are of great interest. In fact, several biological activities, such as antioxidant, antimicrobial, anticariogenic, anti-inflammatory, antihypertensive, and antiglycative activities, have been attributed to coffee melanoidins. To understand the potential of coffee melanoidin health benefits, it is essential to know their chemical structures. The studies undertaken to date dealing with the structural characterization of coffee melanoidins have shown that polysaccharides, proteins, and chlorogenic acids are involved in coffee melanoidin formation. However, exact structures of coffee melanoidins and mechanisms involved in their formation are far to be elucidated. This paper systematizes the available information and provides a critical overview of the knowledge obtained so far about the structure of coffee melanoidins, mechanisms of their formation, and their potential health implications.
Article
Thirty-five representative and suitably selected roasted coffee samples were characterised by near-infrared (NIR) spectroscopy and used to prepare the corresponding espresso samples to be subsequently subjected to sensory evaluation by trained panellists. The main purpose was to investigate the relationships between certain crucial sensory attributes of espresso coffees, including perceived acidity, mouthfeel, bitterness and aftertaste, and near-infrared spectra of original roasted coffee samples, in such a way that non-destructive near-infrared reflectance measurements would be used to predict all these sensory properties with a decisive influence from a quality assurance standpoint. Separate calibration models based on partial least squares regression (PLS), correlating NIR spectral data of roasted coffee samples with each sensory attribute of espresso samples studied, were developed. Wavelength selection was also performed applying iterative predictor weighting–PLS (IPW–PLS) in order to take into account only significant and characteristic spectral features, in an attempt to improve the quality of the final regression models constructed. Using IPW–PLS regression, prediction of the four sensory responses modelled was performed with high accuracy, with root mean square errors of the residuals in cross-validation (RMSECV) ranging from 4.7 to 7.0%. Thus, the results provided by the high-quality calibration models proposed in the present study, comparable in terms of accuracy to the evaluations provided by a trained sensory panel, are promising and prove the feasibility of using a similar methodology in on-line or routine applications to predict the sensory quality of unknown espresso coffee samples via their respective NIR roasted coffee spectra.
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Naturally occurring aroma compounds are able to elicit physiological and migratory responses such as chemotaxis even at nano to femtomolar concentrations in organisms at different levels of phylogeny. Despite the amazing chemical variety of these substances the apparatus by which they can be detected i.e. the chemosensory receptors and the signaling pathways seem to be rather uniform and evolutionary well-conserved. The intracellular signaling process is supposed to be mediated by either cAMP or inositol 1,4,5-trisphosphate. The present work aimed to investigate the chemotactic behavior of 11 odorants that occur naturally in foods and are also used by the industry as additives, on the eukaryotic ciliate Tetrahymena pyriformis. Intracellular signaling pathways that might be activated by these compounds were also investigated. Activation of the phospholipase C (PLC) was measured by FACS and the stimulation of inositol-1,4,5-trisphosphate 3-kinases (IP3K) was measured using two specific inhibitors, wortmannin and LY294002. The strongest chemoattractant character was observed for isoamyl acetate (10(⁻6) M), propyl isobutyrate (10(⁻8) M), isobutyl propionate (10(⁻6) M). The strongest repellent action was exerted by benzyl acetate (10(⁻8) M), furfuryl thioacetate (10(⁻12) M). Our results suggest that Tetrahymena responds in a very sensitive way to slight changes in the molecular structure. According to our study, tracer amounts of solvents do not contribute significantly to the chemotactic profile of the respective odorants. No significant activation of PLC or PI3K could be observed following stimulation with attractant odorants which implies that some other pathways may be involved, hence further investigation is needed.
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Printout. Thesis (M.S.)--Oregon State University, 2005. Includes bibliographical references.
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We investigated odour-active trace compounds in roasted Brazilian Arabica coffee. Aroma dilution extract analysis (AEDA) applied to the volatile oil extracted from roasted coffee brew revealed 34 odour-active compounds. Among these, a pungent-smelling unknown odour-active compound was determined. The volatile oil was fractioned by silica gel column chromatography. Gas chromatography-olfactometry (GC-O) and multidimensional gas chromatography-mass spectrometry (MDGC-MS) of the fraction which contained a significant amount of the target unknown compound revealed the cyclic 1,4-diketone, cis-2,6-dimethyl-1,4-cyclohexanedione, which had a pungent odour, and was thus first identified in roasted coffee. Model experiments revealed that cis-2,6-dimethyl-1,4-cyclohexanedione was formed via thermal degradation of sugars, especially monosaccharides, under alkaline conditions. Further, we demonstrated that 2-hydroxy-3-pentanone and 1-hydroxy-2-propanone, thermal degradation products of monosaccharides, were closely related to the formation of cis-2,6-dimethyl-1,4-cyclohexanedione.
Article
The effect of pH on the thermal stability of potent roasty odorants, 3-mercapto-3-methylbutyl esters, in coffee drinks was investigated. The concentration of 3-mercapto-3-methylbutyl formate in the coffee drink was drastically decreased during the heat processing. However, the residual ratio of this compound in the coffee drink adjusted to pH 5.0 was higher than that of pH 6.5. On the other hand, the residual ratios of 3-mercapto-3-methylbutyl acetate showed high values in the coffee drinks adjusted to both pHs. In the pH range of 3-7, the residual ratios of 3-mercapto-3-methylbutyl formate in aqueous model solutions varied depending on the pH value. It had a thermal stability maximum at pH 4.0, while 3-mercapto-3-methylbutyl acetate showed stability during heat processing over all the pH values tested. In addition, the residual ratios of the formate and acetate esters, which were composed of various alcohol derivatives, showed the same tendency as that of the 3-mercapto-3-methylbutyl esters. These results suggested that the low thermal stability and pH dependence of 3-mercapto-3-methylbutyl formate are based on the structure of the formate ester.
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The current work studies the potent odorants of roasted coffee from the variety Coffea Canephora from Espirito Santo State, Brazil. The coffee samples were roasted at three degrees: light, medium and dark. The medium roast presented the greatest content on essential oil. The GC/MS analysis allowed the quantification of 161 compounds (pick area over 0.07%) and 123 were identified, from which 19 were characterized as potent odorants. The extremely potent odorant β-damascenone was responsible for 76 % of the total odorific activity at the light roast, and this activity decreased to 64 % at the dark roast. The accentuated fruity, flower and tea odor of β-damascenone makes the conilon coffee very different in comparison to arabica coffee, mainly at the light roast.
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Tea and coffee drinks canned or bottled in polyethylene terephthalate (PET) containers are the most important commercial soft drinks in Japan, and a high-quality favor is desirable. However, it has been difficult to realize this, especially in terms of providing a natural and characteristic flavor and maintaining the fresh flavor of homemade tea infusions and coffee brews. Scientific knowledge of the chemistry of tea and coffee drink flavors has made much progress in recent years. This paper reviews the progress of the flavor chemistry of potent odorants in Japanese green (Sen-cha) infusion and roasted coffee brew, and the deterioration of tea and coffee flavors during the manufacturing process of commercial drinks.
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This paper reports a study on the adsorption of the aroma component 2-phenylethanol from an aqueous solution onto granular activated carbon, derived from coconut husks, using batch and continuous (packed-bed column) systems. In the batch mode, the contact time required to attain the adsorption equilibrium was 90 min. The adsorption isotherms were evaluated at 20.0 °C, 30.0 °C and 40.0 °C. In the continuous mode, the effects of flow rate and bed length were studied. Experimental data showed that the breakthrough and exhaustion times decreased with higher flow rates and increased with higher packed beds. The adsorption in the fixed-bed column was more efficient under the following conditions: flow rate of 3.5 mL min−1 and bed length of 11 cm. Based on the data acquired, adsorption appears to represent a promising method for the recovery of 2-phenylethanol lost during the instant coffee production process.
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This study aimed to evaluate the effect of coffee decaffeination with dichloromethane on the in vitro antioxidant activity of this matrix. It were determined the content of total phenolics, chlorogenic acid and caffeine of the coffee samples. The assessment of the antioxidant potential was investigated by DPPH radical scavenging method, reducer power and Fe2+chelation activity. The process of decaffeination and roasting caused changes in the levels of the compounds investigated. The results show that the decaffeination by the dichloromethane method reduces the in vitro antioxidant potential of coffee.
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Two aroma compounds of volatile thiols, 2-furanmethanethiol (2FM) and ethyl 2-mercaptopropionate (ET2MP), were formed in five types of Japanese soy sauce during fermentation by yeast. The concentrations of 2FM and ET2MP in the soy sauce samples increased during alcoholic fermentation. The concentrations of 2FM and ET2MP were higher in the soy sauce fermented by Zygosaccharomyces rouxii than in that fermented by Candida versatilis. The enantiomers of ET2MP were separated by gas chromatography in a capillary column. The average enantiomeric ratio of ET2MP in the soy sauce was approximately 1:1. 2FM was formed by yeast in a medium prepared from cysteine and furfural, and cysteine is considered the key precursor of 2FM by yeast in soy sauce.
Article
This study was done to provide basic information about the storage and distribution of specialty grade coffee of which the market will be expanded through customer sensory evaluation according to the storage period of specialty grade coffee by the SCAA classified method with consideration to defective beans and scent. The specialty grade coffee sample of this study was extracted on day 1, day 14, and day 28. The water content showed a significant reduction on the 28th storage day and there was no pH change according to the storage period. Color degree was brightened according to the preservation period before and after grinding but there was no significant difference. The panels for sensory evaluation considered of 24 university. The sensory evaluation consist of aroma, bitterness, and astringency, acidity, aftertaste, overall satisfaction, and items for strength estimation consist of aroma, acidity and bitterness. The sensory evaluation was expressed by applying a 5 point Likert scale. The results showed that as the storage period increased so too did the aroma and the strength of bitterness. Preference was the highest on day 1 in every items except aroma and astrigency. However on day 14 and day 28, most of the sensory evaluation became low and then became high, which was inconsistent. Male students were not consistent in their evaluation according to the preservation period, but female students rated aroma and bitterness the lowest on preservation period day 1 and they prefer after a storage period of 1 day in regards to the entire degree of satisfaction including sour test. astrigency and aftertaste. The analysis of visiting frequency for coffee shops used demonstrated that the longer the preservation period, the lower the preference but was not significant in the case of involving a little frequency group. The group that did not like Americano coffee evaluated that the longer the preservation period, the lower the preference based on Americano coffee preference analysis. There was no consistency between the storage period day 14 and day 28 in strength and preference, but preference for storage period day 1 was high in every group, which means that the quality of coffee is affected by the preservation period.
Article
Japan has a wide variety of commercial beverage products compared to the rest of the world. Tea (green, black, oolong, etc.), coffee, and fruit juice (especially citrus) beverages are the main product groups. For beverages providing a mellow and attractive flavor, aroma is one of the most important factors affecting quality and thereby product value. Generating a product with high quality aroma and good palatability poses significant challenges during product quality improvement. Therefore, to create attractive beverage products, fundamental knowledge of the key aroma constituents (potent and off-flavor odorants), as well as their chemical and sensory behaviors, in beverages has been strongly needed. In this article, our research about potent and off-flavor odorants and their characteristics in teas (Sen-cha, pan-fired green tea, and Ceylon black tea), coffee, and citrus fruit juices, based on the Aroma Extract Dilution Analysis (AEDA) technique, is described.
Chapter
Maillard reaction, lipid oxidation, degradation of sugars, proteins, lipids, ribonucleotides, pigments and vitamins, and the interactions of degradation products are the chemical platform for generating many flavor compounds encountered in process and reaction flavors, flavorings and foods. The flavor industry is by far the largest user of knowledge from process/and reaction flavor studies and has grown from approximately 2 billions, 20 years ago, to about 8 billion dollars in annual sales today. During the last few decades, much progress in the understanding and utilization of process flavors was made due to advances in chromatographic separation and computer-related technology, relentless investigation of a wide range of flavor precursors, regulation that met consumer safety concerns, and industry demand for better, complex and authentic products. This symposium was organized to shed some light on the current state of science in process and reaction flavors, and to report recent significant findings.
Chapter
Volatile methional (3-methylthiopropanal) is the characteristic flavor compound responsible for the particular aroma of cooked potato. Potato snacks, especially potato chips, are among the most popular foods in the snack-food market. An extrusion process has been used extensively to produce low-fat and fat-free potato snacks while retaining the desirable texture and flavor. Potato cultivars and storage time greatly affect the volatile flavor components of baked potato. Methional was found to be one of the major potent odorants in tea during heat processing measured by gas chromatography-mass spectrometry in aroma extract dilution analysis. Met is the only sulfur-containing amino acid that is essential for mammals and needs to be derived entirely from the diet. Considering the autogenous control mechanism from Met-dependent downregulation of cystathionine γ-synthase (CGS) expression, these results indicate that the autogenous control can be overcome by increasing the level of CGS mRNA through transcriptional control.
Article
The odorants contributing to the characteristic aroma of Matcha were investigated by analysis of the headspace samples and the volatile fractions prepared by a combination of solvent extraction and the SAFE techniques using three Matcha powders of different grades (high, medium, and low). Gas chromatography-olfactometry of the headspace samples (GCO-H) and the aroma extract dilution analysis (AEDA) applied to the volatile fractions revealed 16 (FD factor ≥1) and 39 (FD factor ≥4³) odor-active peaks, respectively. Among them, 14 and 37 of the odorants, most of which were newly detected in Matcha, were identified or tentatively identified by GC-MS and GC-O, respectively. By comparing the perceived odorants of the three Matcha powders, it was revealed that eight compounds showed high flavor dilution (FD) factors irrespective of the grades; i.e., 4-hydroxy-2,5-dimethyl-3(2H)-furanone (sweet), coumarin (sweet), 3-methyl-2,4-nonanedione (green), (E,Z)-2,6-nonadienal (green), trans-4,5-epoxy-(E)-2-decenal (metallic), (Z)-1,5-octadien-3-one (metallic), α-ionone (floral), and (E)-isoeugenol (floral). In addition, some odorants were suggested to influence the characteristic aroma of each grade. Furthermore, trans-4,5-epoxy-(E)-2-decenal, one of the potent odorants of Matcha, was revealed to exist as a racemic form in Matcha. This result suggested that trans-4,5-epoxy-(E)-2-decenal is formed by a non-enzymatic reaction in Matcha, different from that in black tea, and that the unique manufacturing process of Matcha has a close connection with its formation.
Article
Practical application: Ready-to-drink (RTD) milk coffee manufactured using the conventional blending-before-sterilization process does not retain its original coffee flavor due to pH adjustment of the coffee during the process. The new blending-after-sterilization (BAS) process enabled the production of RTD milk coffee whose volatiles are closer to that of homemade milk coffee, as demonstrated by the results of RAS-GC-MS analysis. The BAS process has already been applied to the manufacture of RTD milk coffees in Japan.
Article
Whey protein hydrolysates (WPH) were prepared from whey protein concentrate (WPC) by partial or extensive hydrolysis. WPC and two WPH types were characterized by a descriptive sensory analysis. WPC exhibited a “milky”, “sweet”, and “mild milk fat” odor, whereas extensively hydrolyzed whey protein (E‐WPH) demonstrated “cheese‐like”, “acrid odor”, and “sour” olfactory characteristics. In E‐WPH, 3‐(methylthio)‐propanal, phenylacetaldehyde, and 3‐methylbutanoic acid were specifically detected with high flavor dilution factors upon aroma extract dilution analysis. These odor‐active compounds likely contributed to the olfactory characteristics of E‐WPH, and their concentration increased together with that of their respective putative precursors: free methionine, phenylalanine, and leucine.
Article
To develop a ready‐to‐drink (RTD) milk coffee that retains the original coffee flavor, the effects of manufacturing processing conditions on retronasal‐aroma (RA) odorants were investigated by gas chromatography‐olfactometry (CharmAnalysis™) using an RA simulator (RAS). Twenty‐nine of 33 odorants detected in the RAS effluent (RAS odorants) were identified. The detected odorants were classified into 19 odor‐description groups. The total odor intensity (charm value, CMV) of all coffee RAS odorants decreased approximately 68% following pH adjustment, whereas the total CMV increased 6% to 7% following ultra‐high‐temperature sterilization. The total CMV ratio (about 83%) of the milk coffee produced using a new blending‐after‐sterilization (BAS) process without pH adjustment of the coffee was greater than that (approximately 56%) prepared using a conventional blending‐before‐sterilization (BBS) process with pH adjustment. In BAS‐processed milk coffees, the total CMV ratio (91%) with infusion (INF)‐sterilized reconstituted milk (r‐milk) was greater than that (83%) of plate (PLT)‐sterilized r‐milk. Principal component analysis of odor‐description CMVs indicated that the effect of coffee pH adjustment on odor characteristics was greater than that of sterilization, that BAS and BBS samples differed, and that BAS milk coffee prepared using INF sterilization was more similar to homemade milk coffee (blending unsterilized coffee without pH adjustment with PLT‐sterilized milk) than milk coffee prepared using PLT sterilization. In conclusion, the BAS process using INF sterilization is superior for manufacturing RTD milk coffee that retains odor characteristics similar to targeted homemade milk coffee. Practical Application Ready‐to‐drink milk coffee beverages produced using conventional blending‐before‐sterilization methods do not retain their original coffee flavor following adjustment of the pH of the coffee during manufacturing. The use of newly developed blending‐after‐sterilization methods, by contrast, produces ready‐to‐drink milk coffee with an aroma more similar to that of homemade milk coffee, as demonstrated using an analytical system for characterizing food product aromas. The blending‐after‐sterilization process is now being used in Japan to produce ready‐to‐drink milk coffee beverages.
Article
This study is the first of two publications that investigate the phenomena of coffee nonvolatiles interacting with coffee volatile compounds. The purpose was to identify which coffee nonvolatile(s) are responsible for the interactions observed between nonvolatile coffee brew constituents and thiols, sulfides, pyrroles, and diketones. The overall interaction of these compounds with coffee brews prepared with green coffee beans roasted at three different roasting levels (light, medium, and dark), purified nonvolatiles, and medium roasted coffee brew fractions (1% solids after 1 or 24 h) was measured using a headspace solid-phase microextraction technique. The dark roasted coffee brew was slightly more reactive toward the selected compounds than the light roasted coffee brew. Selected pure coffee constituents, such as caffeine, trigonelline, arabinogalactans, chlorogenic acid, and caffeic acid, showed few interactions with the coffee volatiles. Upon fractionation of medium roasted coffee brew by solid-phase extraction, dialysis, size exclusion chromatography, or anion exchange chromatography, characterization of each fraction, evaluation of the interactions with the aromas, and correlation between the chemical composition of the fractions and the magnitude of the interactions, the following general conclusions were drawn. (1) Low molecular weight and positively charged melanoidins present significant interactions. (2) Strong correlations were shown between the melanoidin and protein/peptide content, on one hand, and the extent of interactions, on the other hand (R = 0.83-0.98, depending on the volatile compound). (3) Chlorogenic acids and carbohydrates play a secondary role, because only weak correlations with the interactions were found in complex matrixes.
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Aroma extract dilution analysis (AEDA) revealed 13 compounds as important contributors to the aroma of roasted coffee (powder): 2-methyl-3-furanthiol (I), 2-furfurylthiol (II), methional (III), 3-mercapto-3-methylbutylformate (IV), 3-isopropyl-2-methoxypyrazine (V), 2-ethyl-3,5-dimethylpyrazine (VI), 2,3-diethyl-5-methylpyrazine (VII), 3-isobutyl-2-methoxy-pyrazine (VIII), 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolon, IX), 4-ethylguaiacol (X), 5-ethyl-3-hydroxy-4-methyl-2(5H)-furanone (XI), 4-vinylguaiacol (XII), and (E)--damascenone (XIII). A comparative AEDA of the coffee powder and brew showed in the brew an increase of III, IX, vanillin and 4-hydroxy-2,5-dimethyl-3(2H)-furanone and a decrease of I, II, IV, V, VII, and VIII.Die Aromaextrakt-Verdnnungsanalyse (AEVA) von Rstkaffee ergab 13 wichtige Geruchsstoffe: 2-Methyl-3-furanthiol (I), 2-Furfurylthiol (II), Methional (III), 3-Mercapto-3-methylbutylformiat (IV), 3-Isopropyl-2-methoxypyrazin (V), 2-Ethyl-3,5-dimethylpyrazin (VI), 2,3-Diethyl-5-methylpyrazin (VII), 3-Isobutyl-2-methoxypyrazin (VIII), 3-Hydroxy-4,5-dimethyl-2(5H)-furanon (Sotolon, IX), 4-Vinylguajacol (XII) und (E)--Damascenon (XIII). Die vergleichende AEVA von Rstkaffee und daraus hergestelltem Aufgu zeigte im Aufgu eine Zunahme von III, IX, Vanillin und 4-Hydroxy-2,5-dimethyl-3(2H)-furanon und eine Abnahme von I, II, IV, V, VII und VIII.
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We have investigated the changes in flavor of a coffee drink during sterilization heating. Gas chromatography-Olfactometry (GC-O) revealed that five potent aroma compounds (2-furfurylthiol, methional, 3-mercapto-3-methylbutyl formate, β-damascenone, and skatole) made significant contributions to the difference between heating and non-heating. Furthermore, the behavior of these five aroma compounds was studied in detail using a model system. The residual ratios for these compounds after heating were 0.3-79.0%. Especially, the three sulfur compounds showed low ratios (2-furfurylthiol : 3.6%, methional : 26.0%, 3-mercapto-3-methylbutyl formate : 0.3%). The volatile compounds obtained from 2-furfurylthiol, methional, and 3-mercapto-3-methylbutyl formate after heating included difurfuryl disulfide, which was accompanied by 2-furfural and 2-furfuryl alcohol, dimethyl disulfide, and 3-mercapto-3-methylbutanol, respectively. These results suggested that potent aroma compounds in a coffee drink were changed by oxidation, thermal degradation, and/or hydrolysis during heating.
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Dilute ethereal solutions of mercaptoacetone (MA), 2-mercapto-3-butanone (MB), 3-mercapto-2-pentanone (MP), 2-methyl-3-furanthiol (MFT), and 2-furfurylthiol (FFT), either alone or in pairs, were stored at 6 °C. During a period of 10 days the oxidation of the thiols to the corresponding disulfides or mixed disulfides was followed by high-resolution gas chromatography/mass spectrometry. In diethyl ether MFT showed the highest oxidation rate, which decreased in the order MFT MA > MB = MP = FFT. After 1 day, mixed disulfides (e.g. MFT−FFT, FFT−MB) were detectable when pairs of the five thiols dissolved in diethyl ether were stored at 6 °C. MFT oxidized more slowly in dichloromethane than in diethyl ether, and it was stable in pentane. However, a heat treatment increased the oxidation rate of MFT dissolved in dichloromethane or pentane. Keywords: 2-Methyl-3-furanthiol; 2-furfurylthiol; disulfide formation
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The volatiles forming the pleasant odour arising from freshly roasted coffee beans were investigated by means of an improved headspace technique with intermediate cryo-focusing and simultaneous sniffing analysis. Shelf-life tests were carried out with whole beans in non-air tight packs and indicated that the loss of aroma freshness several days to weeks after roasting corresponded to the decrease in certain low boiling volatiles, mainly methanethiol. To validate the method, several starting parameters were investigated, specifically the influence of particle size, degree of roasting and coffee bean origin. Results reveal that this headspace technique allows an objective evaluation of the aroma freshness of whole coffee beans without exact knowledge of coffee origin, degree of roasting or starting values. In addition the method differentiates between Arabica and Robusta coffees.Die Zusammensetzung des angenehmen Aromas, das von frisch gersteten Kaffeebohnen ausgeht, wurde mit einer Headspace-Methodik unter Einschaltung eines Cryofocussierungsschrittes sowie paralleler Schnffelanalyse untersucht. Kinetische Studien mit ganzen Rstkaffeebohnen, die in nicht luftdichter Verpackung gelagert wurden, ergaben, da die lagerungsbedingte Abnahme der Aromafrische mit dem Verlust bestimmter leichtflchtiger Verbindungen insbesondere Methanthiol korreliert. Zur Validierung der Methode wurde der Einflu verschiedener Parameter z. B. Mahlgrad, Rstgrad oder Provenienz, untersucht. Die Ergebnisse legen nahe, da die entwickelte Methodik zur objektiven Beurteilung der Aromafrische ganzer Rstkaffeebohnen eingesetzt werden kann und zwar in weiten Bereichen ohne spezielle Kenntnis der Kaffee-Herkunft, des Rstgrades sowie anderer Einflugren. Darber hinaus ist eine analytisch-chemische Differenzierung zwischenArabica undRobusta-Einzelprovenienzen mglich.
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The highly volatile, potent odorants of coffee samples were evaluated by gas chromatography-olfactometry of decreasing headspace samples (GCO-H). 2,3-Butanedione, 2,3-pentanedione, 3-methyl-2-butenthiol (I), methional, 2-furfurylthiol (II) and 3-mercapto-3-methylbutylformate (III) were the key odorants of both, the powders of Arabica and Robusta coffees. 2-Methyl-3-furanthiol (IV), 2,3-diethyl-5-methylpyrazine and an unknown compound were additional key odorants of the latter. An increase in the odour potencies of acetaldehyde, propanal, methylpropanal, 3-methylbutanal and dimethyltrisulphide as well as a decrease in the odour potencies of the thiols I to IV in the brews were the major differences with regard to the powders.
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Aroma extract dilution analysis (AEDA) is a quantitative gas chromatography olfactometry (GCO) procedure for determining the potency of odorants in food extracts. After the odorants with the highest flavour dilution factors have been identified, their concentrations in foods are quantified and their odour activity values (OAVs) are calculated. Applications of this new method to the study of several flavours and off-flavours are reviewed.
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The concept of flavour analysis developed in our laboratory during the last decade to evaluate the key odorants of foods and beverages, is demonstrated in a review on coffee flavour. The results obtained by aroma extract dilution analysis (AEDA), gas chromatography/olfactometry of headspace samples and quantitation of potent odorants using corresponding stable isotopomers as internal standards are discussed. Finally, some sensory experiments performed on the basis of data assessed by instrumental analyses of roasted coffee samples are reported.
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Addition of the total melanoidin fraction isolated by water extraction from medium-roasted coffee powder to a model solution containing a set of 25 aroma compounds mimicking the aroma of a coffee brew reduced, in particular, the intensity of the roasty, sulfury aroma quality. Model studies performed by static headspace analysis revealed that especially three well-known coffee odorants, that is, 2-furfurylthiol (FFT), 3-methyl-2-butene-1-thiol, and 3-mercapto-3-methylbutyl formate, were significantly reduced in the headspace above an aqueous model solution when melanoidins were added. In particular, the low molecular weight melanoidins (1500-3000 Da) led to the most significant decrease in FFT. In contrast, for example, aldehydes remained unaffected by melanoidin addition.
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The flavor stability of an aqueous solution of a savory model process flavoring based on ribose and cysteine was investigated during accelerated storage at 50 degrees C. Of the three sulfur-containing flavor-impact components investigated, 2-methyl-3-furanthiol was found to be the least stable (59% decrease/24 h), and it was followed by 2-furfurylthiol (28% decrease/24 h), 2-mercapto-3-butanone (14% decrease/24 h), and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (max. 10% decrease/24 h). Both cysteine and ribose were found to affect the stability of various flavor compounds. A mechanism for the instability of 2-methyl-3-furanthiol is proposed, and was confirmed by H-D exchange experiments.
Article
Comparative aroma dilution analyses of the headspaces of aqueous solutions containing either the total volatiles isolated from a fresh coffee brew, or these volatiles remixed with the melanoidins isolated from coffee brew, revealed a drastic decrease in the concentrations of the odorous thiols 2-furfurylthiol, 3-methyl-2-butenthiol, 3-mercapto-3-methylbutyl formate, 2-methyl-3-furanthiol, and methanethiol when melanoidins were present. Among these thiols, 2-furfurylthiol was affected the most: e.g., its concentration decreased by a factor of 16 upon addition of melanoidins. This was accompanied by a decrease in the overall roasty-sulfury aroma. Quantitations performed by means of stable isotope dilution assays confirmed the rapid loss of all thiols with increasing time while keeping the coffee brew warm in a thermos flask. Using [2H2]-2-furfurylthiol as an example, [2H]-NMR and LC/MS spectroscopy gave strong evidence that thiols are covalently bound to the coffee melanoidins via Maillard-derived pyrazinium compounds formed as oxidation products of 1,4-bis-(5-amino-5-carboxy-1-pentyl)pyrazinium radical cations (CROSSPY). Using synthetic 1,4-diethyl diquaternary pyrazinium ions and 2-furfurylthiol, it was shown that 2-(2-furyl)methylthio-1,4-dihydro-pyrazines, bis[2-(2-furyl)methylthio]-1,4-dihydro-pyrazines, and 2-(2-furyl)methylthio-hydroxy-1,4-dihydro-pyrazines were formed as the primary reaction products. Similar results were obtained for models in which either 1,4-diethyl diquaternary pyrazinium ions were substituted by Nalpha-acetyl-L-lysine/glycolaldehyde, or the 2-furfurylthiol by 2-methyl-3-furanthiol and 3-mercapto-3-methylbutyl formate. On the basis of these results it can be concluded that the CROSSPY-derived pyrazinium intermediates are involved in the rapid covalent binding of odorous thiols to melanoidins, and, consequently, are responsible for the decrease in the sulfury-roasty odor quality observed shortly after preparation of the coffee brew.
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The stability of the coffee flavor compound furfuryl mercaptan has been investigated in aqueous solutions under Fenton-type reaction conditions. The impact of hydrogen peroxide, iron, ascorbic acid, and ethylenediaminetetraacetic acid was studied in various combinations of reagents and temperature. Furfuryl mercaptan reacts readily under Fenton-type reaction conditions, leading to up to 90% degradation within 1 h at 37 degrees C. The losses were lower when one or more of the reagents was omitted or the temperature decreased to 22 degrees C. Volatile reaction products identified were mainly dimers of furfuryl mercaptan, difurfuryl disulfide being the major compound. In addition, a large number of nonvolatile compounds was observed with molecular masses in the range of 92-510 Da. The formation of hydroxyl and carbon-centered radicals was indicated by electron paramagnetic resonance spectra using alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone or 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide as spin traps. Whereas *OH was generated by Fenton-type reactions, the C-centered radical is probably a secondary product of the reaction of *OH with various organic molecules, the reaction with furfuryl mercaptan appearing to be the most important. No evidence for S-centered radicals was seen in the spin-trapping experiments, but a sulfur-containing radical was detected when measurements were made at 77 K in the absence of spin traps.
A method for producing stable coffee drinks13) Grosch, W. Detection of potent odorants in foods by aroma extract dilution analysis
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